Cholesterol "Red and Black List" and Pathways to Optimize Blood Lipids: Medical Science Popularization on Differentiating High-Density Lipoproteins and Adjusting Dietary Structure

Cholesterol has an absorption rate of only 30%, and this rate decreases further as the cholesterol content of food increases. 200 milligrams of cholesterol is roughly equivalent to the cholesterol content of one egg or the cholesterol absorbed from 3-4 eggs. Excessive dietary cholesterol intake leads to high blood cholesterol levels, which can cause various diseases such as atherosclerosis and gallstones. Therefore, it is crucial for the general population, especially the middle-aged and elderly and obese individuals, to limit their intake of high-cholesterol and high-fat foods to prevent coronary heart disease. Foods high in cholesterol include egg yolks, crab roe, crab paste, animal brains, liver, kidneys, and cuttlefish.

The cholesterol content per 100 grams of crab meat, crab roe, and pork liver is 235 mg, 460 mg, and 368 mg, respectively. Foods with no cholesterol or low cholesterol content include all plant-based foods, egg whites, poultry, dairy products, and fish. Cholesterol exists in the blood as lipoproteins, including high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein cholesterol (VLDL-C). HDL-C is a plasma lipoprotein that protects against atherosclerosis and is a protective factor against coronary heart disease, commonly known as a "vascular cleanser."

It acts as a transporter, collecting excess cholesterol from food or the liver and carrying it to the liver for breakdown. Therefore, HDL helps clear cholesterol from cells and is considered "good" cholesterol. The normal reference range for HDL is 0.7–2.0 μmol/L. Conversely, low-density lipoprotein (LDL) transports cholesterol produced by the liver to cells throughout the body. Two-thirds of LDL in the body is cleared by the liver and extrahepatic tissues through metabolism, while the remaining one-third is cleared through a "scavenger" pathway (macrophages).

Macrophages engulf cholesterol in LDL, causing it to remain inside the cell and forming "foam" cells. When LDL, especially oxidized low-density lipoprotein (OX-LDL), is excessive, the cholesterol it carries deposits on the arterial walls, potentially leading to arteriosclerosis over time. Therefore, LDL is also called "bad" cholesterol and is generally considered a precursor to cardiovascular disease. Elevated cholesterol and LDL levels are related to an unhealthy diet, lack of exercise, obesity, excessive stress, and depression. Therefore, paying attention to a balanced diet, regular exercise, and maintaining a positive mood in daily life can effectively lower blood cholesterol and LDL levels.

Specific measures include: reducing or eliminating consumption of foods extremely high in cholesterol, such as animal organs and egg yolks, and controlling dietary cholesterol intake (less than 300 mg per day). Reduce consumption of fatty meats and animal fats to decrease saturated fatty acid intake. Saturated fatty acids can increase LDL levels in the blood. Increase intake of fiber-rich foods such as vegetables, fruits, and fungi and algae, including celery, corn, oats, konjac, black fungus, kelp, pumpkin, and sweet potatoes. Increasing dietary fiber intake helps lower cholesterol. Regular physical activity, especially moderate-intensity aerobic exercise, helps lower LDL and increase HDL levels.

Consuming moderate amounts of olive oil, tea oil, corn oil, and rapeseed oil is beneficial, as their monounsaturated fatty acids can help lower LDL cholesterol. Moderate alcohol consumption may increase HDL levels in the blood. Daily alcohol intake should ideally not exceed 20 grams (50 grams of spirits). Among these measures, regular physical activity, reducing the intake of high-fat and high-cholesterol foods, and increasing dietary fiber intake are three key factors for maintaining normal blood cholesterol levels and preventing atherosclerosis.